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We are still a week away from the start of Lent but here I am with hot cross buns. Not very traditional - I'm supposed to wait until Good Friday but they've been on sale since Christmas! You can see the heating element on my grill in the photograph. The grill is above the buns so it can't be heating by convection because this is when air heats up, expands and rises. It transfers thermal energy up not down. It could be conduction because that can transfer thermal energy in any direction. However there is air between the heating element and the buns. Air is a good insulator because the molecules are far apart and not joined. They cannot pass on the vibration very easily. In that sense, air is an insulator. So thermal energy must be being transferred by heat radiation. This is in the form of infra-red electromagnetic waves, a type of invisible light. This travels quickly, at the speed of light. It feels warm on our skin because we have receptors cells that detect it. But don't leave your hand under the grill. Heat radiation can burn your hand as well as it will burn toast!
